1. Field of the Invention
The present invention relates to a gamma correction circuit and an image pickup apparatus using such a circuit. In particular, the invention relates to a gamma correction circuit in an apparatus for executing a digital signal process, and an image pickup apparatus using such a circuit.
2. Related Background Art
Miniaturization and reduction in weight of an image pickup apparatus progress in association with the advancement of recent electronic technologies. Among those technologies, are high speed analog/digital converters (hereinafter, referred to as an A/D converters) and digital/analog converters (hereinafter, referred to as a D/A converters) which have been put into practical use. Methods of digital signal processing of a video signal which has been converted into a digital signal using A/D and D/A converters has been proposed with the advancement of semiconductor techniques. According to those methods, the image pickup signal is A/D converted, and signal processing such as filtering, color separation, gamma correction, matrix conversion, and the like are executed by digital processes, and the resultant digital processed signal is D/A converted and output to a utilization device.
However, in an image pickup apparatus using the digital signal processes which has hitherto been proposed, the size of the circuit is large. For example, if a read only memory (ROM) is used to construct a gamma correction circuit, the size such a ROM is large. When all of the signal processing circuits are integrated into a single integrated circuit, therefore, it is difficult to reduce the costs.